The CV keyboard config
The simplest config is for using it just as a CV/Gate keyboard for modular gear. This mode is selected by shorting Pin17 and Pin18 on the chip.

The WASP config This config uses CV/Gate/MIDI-IO and 6 external potentiometers for a WASP style synthesizer. This mode is selected by shorting Pin18 and Pin19 on the chip. This is the same config the Tiny-TS uses.

The full config This uses a rotary encoder and a 128×32 OLED for synth parameter entry. It also has 2 CV inputs on the TRS jack rings and MIDI-IO.

Accessing the board peripherals.

If you want to get just the PCB and do your own programming you need to know how the keyboard, rotary encoder and display are accessed.

Reading the keyboard.

The keyboard is a capacitive touch keyboard just like on the Tiny-TS and Micro-TS.

Because it has 25 keys there aren’t enough GPIO’s to assign for each key. So the keyboard is arranged in a matrix of 5 columns and 5 rows.

Each key on the keyboard have 2 touch pads, 1 from a column and 1 from a row. That totals to 50 touch pads!

The mini-TS does not have a linear regulator and run directly from a 3-5v battery so a trick is required to keep the CV output tuned to 1V/octave. It reads the battery voltage and continuously tune the PWM range. Neat.

The Gate is output on Arduino pin D13.

New are the 2 CV inputs on the CV/Gate TRS jack rings. They are routed to analog pins A2 and A3 through 22K resistors for protection.

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MIDI Interface

The MIDI interface uses the ATmega328 USART port with the MIDI bitrate of 31250bps.

It can use the Arduino MIDI library but you need to add an optocoupler for MIDI input.

DIY for the masses

This is DIY. You can just grab the code here, tape up 50 touch pads with copper tape, breadboard the circuit and it will work.

But I suggest you at the least get the PCB for a professional looking synth and to support my development.

Otherwise It’s all open-source.

One of the mini-TS versions will be the Breadboard synth.
The keyboard provides CV/Gate/MIDI and a square wave oscillator and you may breadboard up any synth you can imagine your self on the breadboard.